Preparation method and application of soil conditioner prepared from industrial tailings

Abstract

The invention relates to a recycling technology of industrial tailings, in particular to a soil conditioner prepared from the industrial tailings, a preparation method of the soil conditioner and application of the soil conditioner in acid cultivated land improvement. The soil conditioner provided by the invention comprises the following components: powder formed by calcining a basic raw material and an additive and then crushing the calcined basic raw material and additive, the basic raw materials comprise the following components in parts by weight: 85-95 parts of phosphate tailings and 2-10 parts of plant straws; the weight part of the additive is 3-5 parts. According to the invention, phosphate tailings and crop straws can be used as main raw materials to prepare the acid soil conditioner, the preparation process is simple, the cost is low, the treatment effect is good, acid cultivated land can be treated, and the soil conditioner can also be applied as a calcium magnesium phosphate fertilizer.

Description

Technical Field

[0001] The invention relates to a recycling technology of industrial tailings, in particular to a soil conditioner prepared from industrial tailings, a preparation method thereof and application of the conditioner in improving acidic cultivated land. Background Art

[0002] The total area of ​​acidic arable land (red soil area) in my country is about 150 million mu, supporting 40% of the population, and rapidly improving the productivity of acidic border arable land. The traditional soil improvement method using limestone as an amendment has problems such as affecting the microbial environment, reducing nutrient utilization, and accelerating soil compaction. Therefore, it cannot be applied continuously and is generally applied once every three years.

[0003] Using industrial waste to treat heavy metal-contaminated farmland can not only promote the reuse of waste resources, but also greatly reduce the cost of heavy metal farmland conditioners. Phosphate tailings are industrial waste produced after crushing and flotation processes in the existing phosphate rock production process. Its main components and weight ratios range from about 5-10% phosphorus pentoxide, 34-45% calcium oxide, and 15-25% magnesium oxide.

[0004] As of 2020, the total amount of stockpiled phosphate tailings in my country is about 1.2 billion tons, with an average of about 10 million tons of phosphate tailings produced each year. Due to the high production and low consumption, the total amount of phosphate tailings is increasing at a rate of 9%. The accumulation of a large amount of phosphate tailings has brought dual pressures on the economy and the environment. Data show that nearly 1 / 3 of my country's tailings reservoirs have major safety hazards and pose a huge potential threat to the ecological environment. On the other hand, phosphate rock has a certain scarcity. In April 2022, the state implemented the "production based on slag" for phosphate mining, and determined the mining volume after the slag was properly processed. The utilization rate of phosphate tailings is less than 10%, and the utilization value is very low. It is currently mainly used for roadbed materials and mine backfill materials. Other applications, such as the separation and production of magnesium carbonate, have too high production costs and almost no economic value. Since the effective phosphorus content in phosphate tailings is far lower than the standard of calcium magnesium phosphate fertilizer (more than 12%), it cannot be used directly as calcium magnesium phosphate fertilizer and is rarely used in soil conditioners.

[0005] As for crop straw, my country produces an average of about 700 million tons of straw every year, and the utilization rate of straw after leaving the field is less than 40%. More than 50% of the straw is directly returned to the field, which will cause an increase in pests and diseases and weeds, and the amount of pesticides will also increase accordingly, increasing the cost of planting. It also affects crop rotation and reduces the utilization rate of cultivated land and per-acre output value. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide an acidic soil conditioner which can utilize phosphate tailings and crop straw as main raw materials, and has simple preparation process, low cost, good treatment effect, can be used to treat acidic cultivated land, and can also be used as a soil conditioner for application of calcium magnesium phosphate fertilizer, as well as its preparation method and application.

[0007] The soil conditioner prepared by utilizing industrial tailings comprises powder obtained by calcining and crushing basic raw materials and additives; the basic raw materials comprise 85 to 95 parts by weight of phosphorus tailings and 2 to 10 parts by weight of plant straws; and the additives comprise 3 to 5 parts by weight.

[0008] Furthermore, the additive includes 1 to 2 parts by weight of manganese sulfate and 2 to 3 parts by weight of silicon dioxide.

[0009] Furthermore, the composition also includes a phosphorus additive, which is a phosphate or a phosphorus oxide, and the weight percentage of the effective phosphorus in the phosphorus additive and the effective phosphorus in the raw material phosphorus tailings in the final product is 6-9%.

[0010] Furthermore, the plant straw is a mixture of one or more of wheat straw, rice straw, corn straw, and rice husk.

[0011] The method for preparing a soil conditioner using industrial tailings of the present invention comprises the following steps:

[0012] 85-95 parts by weight of phosphorus tailings, 2-10 parts of plant straws and 3-5 parts of additives are calcined, cooled and then crushed in a ball mill into a powder product of 70-300 meshes.

[0013] Furthermore, the calcination process is carried out in a rotary kiln at 300-350° C. for 1-1.5 hours, and then at 900-950° C. for 1-2 hours.

[0014] Furthermore, the additive includes 1 to 2 parts by weight of manganese sulfate and 2 to 3 parts by weight of silicon dioxide.

[0015] Furthermore, phosphate is added to the processed material to adjust the content of effective phosphorus to 6-9%.

[0016] Furthermore, the plant straw is a mixture of one or more of wheat straw, rice straw, corn straw, and rice husk.

[0017] The present invention also includes the use of the soil conditioner in improving acidic farmland.

[0018] The positive effects of the present invention are as follows: the porous composite material is obtained by deep processing with phosphorus tailings and straw as main raw materials; the material has a certain alkalinity; the pH value of the aqueous solution is 9-10, the alkalinity is mild, and no damage is caused to the soil; the presence of biochar and additives also has the function of improving the soil microenvironment; the porous property of the material can effectively improve the absorption of calcium, magnesium and phosphorus by crops, and it also has the effect of calcium, magnesium and phosphate fertilizer while treating acidic soil.

[0019] The BET specific surface area of ​​the material is 3.466 m 2 / g; total pore volume is 0.0143m 3 / g, mainly mesopores; the average pore size is 8.986nm, and the mesopore size is 25.935nm. The acid modifier has a large specific surface area and porosity. DETAILED DESCRIPTION

[0020] Embodiment 1:

[0021] 85 kg of phosphorus tailings, 10 kg of rice straw, 2 kg of manganese sulfate and 3 kg of silicon dioxide are calcined in a rotary kiln at 350°C for 1 hour and then at 900°C for 2 hours. After cooling, the mixture is crushed in a ball mill to form a powder product of 80 meshes. Ammonium phosphate is added to the powder product to adjust the weight content of effective phosphorus to 8%, thereby obtaining a product.

[0022] After testing, the product performance parameters are: BET specific surface area is 3.466m 2 / g; total pore volume is 0.0143m 3 / g, mainly mesopores; the average pore size is 8.986nm, and the mesopore size is 25.935nm. The acid modifier has a large specific surface area and porosity.

[0023] The product obtained in Example 1 was tested for performance:

[0024] Test 1-1: The soil conditioner prepared in Example 1 was applied to the soil in different proportions, and a pot test was conducted to test the effect of improving acidity. The test soil was taken from a typical acidic red soil plot at Yingtan Station of the Red Soil Ecological Experimental Station of the Institute of Soil Science, Chinese Academy of Sciences. The test results are shown in Table 1.

[0025] Table 1 Pot test verifies the acid-reducing performance of materials

[0026]

[0027] As shown in Table 1, the material has obvious acidity improvement performance. During the 21-day test, the soil pH value increased by 0.37 with the use of 0.1% material (150 kg per mu of land). The material fully meets the requirements for treating acidic soil (the soil pH value increased by 0.5 in three years).

[0028] Test 1-2:

[0029] Effect of applying acidic soil conditioner on corn plant growth in corn planting field The soil conditioner prepared in Example 1 was used for soil pH improvement test at a soil covering rate of 80 kg / mu.

[0030] Experimental location: Ji'an Station of Red Soil Ecological Experimental Station, Nanjing Institute of Soil Science, Chinese Academy of Sciences;

[0031] Trial period: April 20 to August 22, 2024;

[0032] Test soil: A typical acidic red soil plot (pH 5.21) was used to conduct a test on the fertilizer efficiency of phosphorus tailings at the Red Soil Ecological Experimental Station of the Nanjing Institute of Soil Science, Chinese Academy of Sciences. The cultivated land was a newly reclaimed test site. Soil and harvest corn kernel samples were collected in situ and brought back to the laboratory for soil physical and chemical properties and corn kernel weight analysis. The results are shown in Table 2.

[0033] Table 2 Comparison of compound fertilizer and improver yield

[0034] Serial number Yield (Kg / mu) pH 1 Compound fertilizer 1 (15:15:15) 93.5 5.28 2 Compound fertilizer 2 (containing calcium magnesium phosphate fertilizer) 91.9 5.31 3 Compound fertilizer 3 (including improver) 130.2 5.45

[0035] Note: 1. Compound fertilizer 1 (15:15:15): a compound fertilizer sold on the market, with a nitrogen, phosphorus and potassium content of (15:15:15), and a dosage of 50 kg / mu; 2. Compound fertilizer 2 (containing calcium magnesium phosphate fertilizer): 19.6 kg / mu of urea, 60 kg / mu of calcium magnesium phosphate fertilizer sold on the market, and 12.1 kg / mu of potassium chloride; 3. Compound fertilizer 3 (containing improver): 19.6 kg / mu of urea, 80 kg / mu of the soil improver (effective phosphorus content 8%) of Example 1 (the dosage refers to the local calcium magnesium phosphate fertilizer with an effective phosphorus content of 12%, and the usage equivalent of 60 kg / mu, the dosage ensures that the effective ingredient P 2 O 5 The dosage is equivalent), potassium chloride 12.1kg / mu.

[0036] The data in Table 2 show that after 126 days of field trials, the soil pH of the acidic soil conditioner increased from 5.21 to 5.45, which has a certain effect of improving acidity. The yield increase effect is also significant, which is 1.39 times that of compound fertilizer and 1.42 times that of calcium magnesium phosphate fertilizer. The field test shows that acidic soil conditioners can be applied to newly reclaimed farmland. However, the fertility level of newly reclaimed farmland is very low. The corn yield of local farmland with normal fertility is 1,500 kilograms.

[0037] Embodiment 2:

[0038] 95 kg of phosphorus tailings, 2 kg of rice straw, 1 kg of manganese sulfate and 2 kg of silicon dioxide are calcined in a rotary kiln at 350°C for 1 hour and then at 900°C for 2 hours, and then ground into a 80-mesh powder product in a ball mill after cooling; ammonium phosphate is added to the powder product to adjust the weight content of effective phosphorus to 8% to obtain a product.

[0039] The product obtained in Example 2 was tested for performance:

[0040] Test 2-1: The soil conditioner prepared in Example 1 was applied to the soil in different proportions, and a pot test was conducted to test the effect of improving acidity. The test soil was taken from a typical acidic red soil plot at Yingtan Station of the Red Soil Ecological Experimental Station of the Institute of Soil Science, Chinese Academy of Sciences. The test results are shown in Table 3.

[0041] Table 3 Pot test verifies the acid-reducing performance of materials

[0042]

[0043] As shown in Table 3, the material has obvious acidity improvement performance. During the 21-day test, the soil pH value increased by 0.31 with the use of 0.1% material (150 kg per mu of land). The material fully meets the requirements for treating acidic soil (the soil pH value increased by 0.5 in three years).

[0044] Test 2-2:

[0045] Effect of applying acidic soil conditioner on corn plant growth in corn planting field The soil conditioner prepared in Example 1 was used for soil pH improvement test at a soil covering rate of 80 kg / mu.

[0046] Experimental location: Ji'an Station of Red Soil Ecological Experimental Station, Nanjing Institute of Soil Science, Chinese Academy of Sciences;

[0047] Trial period: April 20 to August 22, 2024;

[0048] Test soil: A typical acidic red soil plot (pH 5.21) was used to conduct a test on the fertilizer efficiency of phosphorus tailings at the Red Soil Ecological Experimental Station of the Nanjing Institute of Soil Science, Chinese Academy of Sciences. The cultivated land was a newly reclaimed test site. Soil and corn kernel samples were collected in situ on site and brought back to the laboratory for soil physical and chemical properties and corn kernel weight analysis. The results are shown in Table 4.

[0049] Table 4 Comparison of compound fertilizer and improver yield

[0050]

[0051] Note: 1. Compound fertilizer 1 (15:15:15): a compound fertilizer sold on the market, with a nitrogen, phosphorus and potassium content of (15:15:15), and a dosage of 50 kg / mu; 2. Compound fertilizer 2 (containing calcium magnesium phosphate fertilizer): 19.6 kg / mu of urea, 60 kg / mu of calcium magnesium phosphate fertilizer sold on the market, and 12.1 kg / mu of potassium chloride; 3. Compound fertilizer 3 (containing improver): 19.6 kg / mu of urea, 80 kg / mu of the soil improver of Example 2 (effective phosphorus content 8%) (the dosage refers to the local calcium magnesium phosphate fertilizer with an effective phosphorus content of 12%, and the usage equivalent of 60 kg / mu, the dosage ensures that the effective ingredient P 2 O 5 The dosage is equivalent), potassium chloride 12.1kg / mu.

[0052] The data in Table 4 show that after 126 days of field trials, the soil pH of the acidic soil conditioner increased from 5.21 to 5.41, which had a certain effect of improving acidity. It has a certain fertilizer effect, but it is not as good as the commercially available compound fertilizer and commercially available calcium magnesium phosphate fertilizer. The field trial shows that the acidic soil conditioner can be applied to newly reclaimed farmland.

Claims

1. A soil conditioner prepared from industrial tailings, characterized in that: its ingredients include powder obtained by calcining and crushing a basic raw material and an additive; the basic raw material includes 85 to 95 parts by weight of phosphate tailings and 2 to 10 parts by weight of plant straw; and the additive includes 3 to 5 parts by weight.

2. The soil conditioner prepared from industrial tailings according to claim 1, characterized in that: The additives include 1-2 parts by weight of manganese sulfate and 2-3 parts by weight of silicon dioxide.

3. The soil conditioner prepared from industrial tailings according to claim 1, characterized in that: Its components also include a phosphorus additive, which is phosphate or phosphorus oxide. The weight percentage of the effective phosphorus in the phosphorus additive and the effective phosphorus in the raw material phosphorus tailings in the final product is 6-9%.

4. The soil conditioner prepared from industrial tailings according to claim 1, characterized in that: The plant straw is a mixture of one or more of wheat straw, rice straw, corn straw and rice husk.

5. A method for preparing a soil conditioner, characterized in that: 85-95 parts by weight of phosphorus tailings, 2-10 parts of plant straws and 3-5 parts of additives are calcined, cooled and then crushed in a ball mill to a powder product of 70-300 meshes.

6. The method for preparing a soil conditioner according to claim 5, characterized in that: The calcination process is to calcine at 300-350° C. for 1-1.5 hours in a rotary kiln, and then calcine at 900-950° C. for 1-2 hours.

7. The method for preparing a soil conditioner according to claim 5, characterized in that: The additive comprises 1 to 2 parts by weight of manganese sulfate and 2 to 3 parts by weight of silicon dioxide.

8. The method for preparing a soil conditioner according to claim 5, characterized in that: Phosphates are then added to the processed material to adjust the effective phosphorus content to 6-9%.

9. The method for preparing a soil conditioner according to claim 5, characterized in that: The plant straw is a mixture of one or more of wheat straw, rice straw and corn straw.

10. Use of the soil conditioner according to any one of claims 1 to 4 in improving acidic farmland.

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